This invention relates to long chain polyamides and more particularly to those polyamides generically known as nylon.
The excellent physical properties of these polyamides makes these compounds useful in manufacture of equipment and machinery parts. The automobile industry for example, has in the past few years, increased its use of parts made from polyamide-containing compositions because of their excellent wear resistance, tensile strength and resistance to corrosion or chemical attack.
Although polyamides generally have excellent corrosion or chemical attack resistance, the polyamides containing 9 or fewer in-chain carbon atoms between each repeating in-chain amide group are subject to stress cracking if they are mechanically stressed and exposed to an aqueous metallic halide solution. Zine chloride has been found to be one of the more active halides with respect to stress cracking of such polyamides.
Experimentation has shown that polyamide compositions such as Nylon 11 containing at least 10 in-chain carbon atoms between each repeating in-chain amide group are not as sensitive to zinc chloride as are polyamides containing 9 or fewer in-chain carbon atoms between each repeating in-chain amide group. The polyamide materials such as Nylon 11 are quite expensive due to the lack of ready availability and the cost of the monomers from which they are prepared. It is desirable to find more suitable, less expensive substitutes having a resistance to attack by zinc chloride.
We have now discovered polyamide compositions that are adapted for use in industrial and consumer oriented components. Conventional molding, casting and extrusion process can be used in the fabrication of the polyamides of this invention. These polyamide compositions also have a resistance to attack by aqueous zinc chloride and other metallic halide solutions provided that the products of this invention are protected from moisture prior to exposure to the aqueous metallic halide solution.
The resistance of these polymers to attack by metallic halide solutions is useful in the manufacture of many articles of commerce e.g. pump impellers, piping, tubing, containers and machinery parts used in the transport of aqueous metallic halide solutions or under environmental conditions which would subject such parts to immersion in or contact with aqueous metallic halide solutions.